JPH0557281B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention is a storage-stable film that substantially does not contain a photopolymerization initiator and can be cured in a short time by irradiation with ultraviolet rays to form an uncolored film with excellent weather resistance. Concerning good UV curable compositions. (Prior Art and Problems to be Solved by the Invention) Ultraviolet curing resins have conventionally been used for painting and adhering inorganic building materials, metal base materials, wood, paper, plastics, and the like. However, in conventional UV-curable resin compositions, in order to obtain a cured film in a short time by UV irradiation, it is necessary to add a photopolymerization initiator of 10% or more, which is usually 3 to 5% more than the resin component. It was hot. Since the photopolymerization initiator is extremely unstable to sunlight and heat, it is necessary to store the coating agent containing it in the above amount and to perform the painting process in a cool, dark place or under special lighting that excludes ultraviolet rays. It was hot. Furthermore, an ultraviolet curable resin composition containing a substantially effective amount of a photopolymerization initiator is colored, and due to the remaining photopolymerization initiator, only a cured film with extremely poor weather resistance can be obtained. Furthermore, the use of expensive photopolymerization initiators poses economical problems. (Technical means for solving the problem) As a result of extensive research in view of the current situation, the present inventors have developed a composition obtained by adding a photopolymerizable compound to a specific (co)polymer. However, even if it does not contain a photopolymerization initiator, it cures in a short time by irradiating it with ultraviolet rays, solving the above problems at once. The present inventors have discovered that it can be suitably used for adhesion and have completed the present invention. That is, the present invention provides an average molecular weight obtained by (co)polymerizing a polymerizable monomer component containing a methacrylate monomer and/or methyl acrylate in a proportion of 10% by weight or more in the polymerizable monomer component. The (co)polymer (A): The photopolymerizable monomer (B) is 40 to 98 (solid content) The present invention relates to an ultraviolet curable composition containing substantially no photopolymerization initiator. The methacrylate monomer used in the present invention is an ester compound of methacrylic acid and a monohydric alcohol or a polyhydric alcohol, and specific examples include methyl, ethyl, propyl, isopropyl methacrylate, Methacrylic acid alkyl esters such as butyl, isobutyl, 2-ethylhexyl, lauryl, stearyl or cyclohexyl ester; hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, phenyl methacrylate,
Diethylaminoethyl methacrylate, mono- or diester of methacrylic acid and polypropylene glycol, mono- or diester of methacrylic acid and polyethylene glycol, methacrylic acid and ethylene glycol, 1,3-butylene glycol, 1,3-hexane glycol neopentyl glycol, etc. Examples include diesters of dihydric alcohols, triesters of methacrylic acid and trimethylolpropane, and one type or a mixture of two or more of these can be appropriately selected and used. Among them, methacrylic acid alkyl esters are most preferred in terms of performance of the ultraviolet curable composition. In the present invention, in addition to the above-mentioned methacrylate monomer and/or methyl acrylate, other polymerizable monomers that can be copolymerized with these may be used in combination, if necessary. Other polymerizable monomers to be used in combination are not particularly limited, and compounds having known polymerizable carbon-carbon double bonds may be optionally used in an amount of less than 90% by weight in the polymerizable monomer component. can. The methacrylate monomer and/or methyl acrylate essential for the polymerizable monomer component are:
Although the reason is not necessarily clear, the use of these has the important effect of imparting ultraviolet curability to the composition consisting of the (co)polymer (A) and the photopolymerizable monomer (B). . The ultraviolet curable composition of the present invention using a methacrylate monomer and/or methyl acrylate is cured at a sufficiently practical rate by irradiation with ultraviolet light even without the addition of any photoinitiator. The amount of methacrylate monomer and/or methyl acrylate used is 10% by weight or more in the polymerizable monomer component, more preferably 30% by weight or more.
% by weight or more. If the amount used is less than 10% by weight, the curing speed and degree of curing of the ultraviolet curable composition will be insufficient and the performance of the film will deteriorate. (Co)polymer (A) can be prepared by known solution polymerization, bulk polymerization,
It can be produced by methods such as emulsion polymerization. The (co)polymer can take the form of a solid, an organic solvent solution, an aqueous dispersion, etc., but it is preferably a solid or an aqueous dispersion that poses no risk of fire or environmental pollution when handled, and is easy to handle. Particularly preferred are aqueous dispersions. The average molecular weight of the (co)polymer (A) needs to be 10,000 or more. If the average molecular weight is less than 10,000, the curing speed of the ultraviolet curable composition may decrease,
The disadvantage is that the performance of the film deteriorates. The photopolymerizable monomer (B) used in the present invention is a compound having at least one radically polymerizable carbon-carbon double bond in its molecule, such as acrylic acid and methyl alcohol, ethyl alcohol, propyl alcohol, Butyl alcohol, hexyl alcohol, octyl alcohol, nonyl alcohol, lauryl alcohol, stearyl alcohol, behenyl alcohol, cyclohexyl alcohol, methoxyethyl alcohol, dicyclopentenyl alcohol, norbornyl alcohol, dicyclopentenyloxy alcohol, tetrahydrofurfuryl alcohol, isobol Esters of monohydric alcohols such as methyl alcohol, benzyl alcohol and phenol; methacrylic acid and methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, hexyl alcohol, octyl alcohol, nonyl alcohol, lauryl alcohol, stearyl alcohol, behenyl alcohol , cyclohexyl alcohol, methoxyethyl alcohol, dicyclopentenyl alcohol, norbornyl alcohol, isobornyl alcohol, dicyclopentenyloxy alcohol, tetrafurfuryl alcohol, benzyl alcohol and phenol.
Esters with monohydric alcohols; mono- or diesters with monohydric alcohols, such as mono- or diesters of fumaric acid, maleic acid or itaconic acid with methyl alcohol, ethyl alcohol, butyl alcohol, octyl alcohol, lauryl alcohol, stearyl alcohol; ; (meta)
Glycidyl acrylate; (meth)acrylic acid and ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (average molecular weight 800 or less), propylene glycol,
Polypropylene glycol (average molecular weight 800 or less), 1,3-butylene glycol, 1,6-hexanediol, neopentyl glycol, bisphenol A, hydrogenated bisphenol A, ethylene oxide of bisphenol A (2 to 4 moles)
Adducts, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol,
Mono-, di-, tri-, tetra-, penta- or hexaesters with polyhydric alcohols such as sorbitol and dipentaerythritol; such as 2-aminoethyl (meth)acrylate, 2-dimethylaminoethyl (meth)acrylate, etc. Meth)acrylic acid aminoalkyl esters; aromatic vinyl monomers such as styrene, vinyltoluene, divinylbenzene, etc.; nitrogen-containing ring-containing monomers such as N-vinylpyrrolidone, vinylpyridine, vinylcarbazole, etc.; diallyl phthalate, etc. One type or a mixture of two or more types can be used.
Among these, di-, tri-, tetra-, penta-, and hexaesters of polyhydric alcohol and (meth)acrylic acid are used to increase the curing rate and degree of curing of the UV-curable composition and improve the performance of the cured film. It is preferable to use at least one selected from the following. It goes without saying that the photopolymerizable monomer (B) serves as a photopolymerizable component in the ultraviolet curable composition of the present invention, but when the (co)polymer (A) is an aqueous dispersion, It also functions as a film-forming aid for the aqueous dispersion, and exhibits the features of the present invention most prominently. As is well known, aqueous dispersions such as emulsion polymers of vinyl monomers have a minimum film formation temperature (MFT).
exists and a continuous film cannot be formed if the ambient temperature during film formation is below MFT.
Conventionally, organic solvents and plasticizers with relatively high boiling points have been used as film-forming aids to reduce MFT, but these substances tend to remain in the film, resulting in a decrease in the hardness of the film. strength decreases,
The drawback was that water resistance and blocking resistance deteriorated. On the other hand, an ultraviolet curable composition comprising an aqueous dispersion as a (co)polymer (A) and a photopolymerizable monomer (B), which is one embodiment of the ultraviolet curable composition of the present invention, can form a film. Sometimes the photopolymerizable monomer (B) acts as a film-forming aid to form a film with good film-forming properties, and when irradiated with ultraviolet rays, it photopolymerizes with the (co)polymer (A). The monomer (B) is cured and integrated. Therefore,
Unlike conventional film-forming aids, low molecular weight compounds do not remain in the film and have no adverse effect, but rather form a film with excellent performance. When the (co)polymer (A) is an aqueous dispersion, the photopolymerizable monomer (B) to be combined should have an average molecular weight of 100 to 1000, a solubility of Parameters 8-12, boiling point at 760mmHg is 100
It is preferable to select a temperature higher than ℃. The above solubility parameter (denoted as δ) is the Group Molar Attraction Constant derived by Hoy from vapor pressure.
(described in J.Paint Technol 42 , 76 (1970)), δ=dΣG/M (d is specific gravity, M is molecular weight,
G is a numerical value calculated by the formula (Group Molar Attraction Constant). Photopolymerizable monomer (B)
When the average molecular weight exceeds 1000, the photopolymerizable monomer (B) becomes difficult to be absorbed by the dispersed particles of the aqueous dispersion, and when the solubility parameter is outside the range of 8 to 12, the photopolymerizable monomer (B) The compatibility between (co)polymer (A) and (co)polymer (A) decreases,
If the boiling point is less than 100℃, the volatility is too high.
In either case, the effectiveness as a film-forming aid decreases. The (co)polymer (A) and the photopolymerizable monomer (B) are such that the (co)polymer (A):the photopolymerizable monomer (B) is 40 to 98% by weight (in terms of solid content). ): Used at a ratio of 60 to 2% by weight. If the ratio of the amount used is outside the above range, the curing speed and degree of curing will decrease, and the performance of the cured film will decrease. To obtain an ultraviolet curable composition from a (co)polymer (A) and a photopolymerizable monomer (B)
When (A) is an aqueous dispersion, both may be stirred and mixed at room temperature under heating or cooling until no residual photopolymerizable monomer (B) is observed. (Both)
When the polymer (A) is a solid or an organic solvent solution, these and the photopolymerizable monomer (B) may be uniformly mixed. The ultraviolet curable composition of the present invention can form a cured film by irradiating it with ultraviolet rays. Of course, curing is also possible by electron beam irradiation. The ultraviolet curable composition of the present invention can be used alone as a coating agent or adhesive for various purposes, but if necessary, a known viscosity modifier, PH modifier, coloring agent, etc. may be added. Good too. (Effect of the invention) The ultraviolet curable composition of the present invention contains a (co)polymer obtained by using a specific monomer in a specific proportion or more and a photopolymerizable monomer in a specific proportion. While conventional ultraviolet curable resins required the addition of several percent of a photopolymerization initiator to the resin, the present invention does not contain a photopolymerization initiator. Regardless, it can be cured by ultraviolet light to form a film with excellent performance. Therefore,
The ultraviolet curable composition of the present invention solves all the disadvantages of conventional ultraviolet curable resin compositions due to photopolymerization initiators, such as high cost, poor storage stability, and poor weather resistance. It is useful as a coating agent for building materials, especially wood and inorganic base materials, a coating agent and adhesive for plastic films, sheets, and molded articles, a coating agent and binder for textile products and paper products, etc. be. (Examples) The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples. In addition, unless otherwise specified in the examples,
Parts represent parts by weight, and % represents weight %. Example 1 1.5 parts of sodium lauryl sulfate, 0.3 parts of potassium persulfate, and 152 parts of water were placed in a flask equipped with a stirrer, an inert gas introduction tube, a dropping funnel, a reflux condenser, and a thermometer.
1 part, heated to 75°C while gently blowing nitrogen gas, stirred to make a homogeneous aqueous solution, and then added 63 parts of methyl methacrylate, 35 parts of ethyl acrylate, and acrylic that had been prepared in advance through a dropping funnel. A polymerizable monomer component consisting of 2 parts of acid was added dropwise over 2 hours. After that, the temperature was maintained at 75℃, and after stirring for another 1 hour, it was cooled to 30℃, and the concentration
Add 28% ammonia water and adjust the pH to 7.5.
An aqueous dispersion of copolymer (1) with a nonvolatile content of 40.1% and an MFT of 50°C or higher was obtained. The average molecular weight of the obtained copolymer 1 was about 150,000. Next, 8 parts of diethylene glycol diacrylate (molecular weight 214, boiling point 200°C or higher, solubility parameter 10.0) as a photopolymerizable monomer was added to 100 parts of the aqueous dispersion of this copolymer (1), and the mixture was heated at 50°C for 1 hour. The mixture was stirred and absorbed into the particles of copolymer (1) to obtain an ultraviolet curable composition (). Example 2 The composition of the polymerizable monomer component was changed to methyl methacrylate.
The same operation as in Example 1 was repeated except that 42 parts of methyl acrylate, 53 parts of methacrylic acid, and 5 parts of methacrylic acid were used to obtain an aqueous dispersion of copolymer (2) with a nonvolatile content of 40.0% and an MFT of 50°C or higher. The average molecular weight of copolymer (2) is approximately 17
It was ten thousand. Next, trimethylolpropane triacrylate (molecular weight 296, boiling point 200°C) was used as a photopolymerizable monomer.
As described above, an ultraviolet curable composition () was obtained in the same manner as in Example 1 using 10 parts of the compatibility parameter (9.5). Example 3 To 100 parts of the aqueous dispersion of copolymer (1) obtained in Example 1, 7 parts of dipentaerythritol hexaacrylate (molecular weight 578, boiling point 200°C or higher, compatibility parameter 10.1) was added as a photopolymerizable monomer. An ultraviolet curable composition () was obtained in the same manner as in Example 1 using a mixture of 3 parts of 2-ethylhexyl acrylate (molecular weight 184, boiling point 219°C, compatibility parameter 8.6). Example 4 0.3 parts of potassium persulfate and 98 parts of water were charged in the same procedure as in Example 1, heated to 65°C while slowly blowing nitrogen gas, stirred to form a uniform aqueous solution, and then poured into a uniform aqueous solution. 100 parts of a polymerizable monomer component consisting of 60 parts of methyl methacrylate, 37 parts of ethyl acrylate, and 3 parts of allyl acrylate prepared in advance from the dropping funnel of No. 1 and Nonipol 400 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Nonion) surfactant) 7 parts and water
Monomer preemulsion prepared from 50 parts
157 parts and 12.6 parts of an aqueous solution of 0.15 parts of sodium bisulfite dissolved in 12.3 parts of water from the second dropping funnel.
part was added dropwise over 3 hours. Then increase the temperature to 75℃
After heating to
An aqueous dispersion of (3) was obtained. The average molecular weight of the obtained copolymer (3) was about 200,000. Next, 20 parts of trimethylolpropane triacrylate (molecular weight 296, boiling point 200°C or higher, compatibility parameter 9.5) and hexamethylene diacrylate (molecular weight 226) were added to 100 parts of the aqueous dispersion of copolymer (3) as photopolymerizable monomers. , boiling point 200°C or above, compatibility parameter 9.5) 10 parts and N-vinylpyrrolidone (molecular weight 111, boiling point 214°C, compatibility parameter
10.6) 10 parts of the mixture was added, stirred at 40°C for 3 hours, and absorbed into the particles of copolymer (3) to obtain an ultraviolet curable composition (). Example 5 The composition of the polymerizable monomer component was changed to methyl methacrylate.
50 parts, butyl acrylate 48 parts and 2 parts acrylic acid
The same procedure as in Example 1 was repeated, except that the dispersion of copolymer (4) with a nonvolatile content of 40.0% and an MFT of 10° C. was obtained. The average molecular weight of copolymer (4) was approximately 160,000. Next, an ultraviolet curable composition () was obtained in the same manner as in Example 1 using 5 parts of trimethylolpropane triacrylate as a photopolymerizable monomer. Comparative Example 1 The same procedure as in Example 1 was repeated except that the composition of the polymerizable monomer components was changed to 63 parts of styrene, 35 parts of ethyl acrylate, and 2 parts of acrylic acid to obtain a non-volatile component.
An aqueous dispersion of Comparative Copolymer (1) having an MFT of 39.8% and a MFT of 50° C. or higher was obtained. The average molecular weight of comparative copolymer (1) was about 130,000. Next, a comparative composition (2) was obtained in the same manner as in Example 1 using 10 parts of trimethylolpropane triacrylate as a photopolymerizable monomer. Comparative Example 2 The same procedure as in Example 1 was repeated except that the composition of the polymerizable monomer components was changed to 50 parts of styrene, 48 parts of butyl acrylate, and 2 parts of acrylic acid to obtain a non-volatile component.
An aqueous dispersion of comparative copolymer (2) with a concentration of 39.9% and a MFT of 8°C was obtained. The average molecular weight of comparative copolymer (2) is approximately 15
It was ten thousand. Next, a comparative ultraviolet curable composition (2) was obtained in the same manner as in Example 1 using 10 parts of trimethylolpropane triacrylate as a photopolymerizable monomer. Example 6 100 parts of toluene was charged into a flask similar to that used in Example 1, heated to 60°C while slowly flowing nitrogen gas, and then 35 parts of methyl methacrylate and acrylic prepared in advance were added thereto. butyl acid
A polymerizable monomer component consisting of 65 parts of benzoyl peroxide and 0.1 part of benzoyl peroxide was added dropwise over 4 hours, and stirring was continued for 8 hours at the same temperature, followed by cooling to room temperature. A solution of copolymer (5) with a nonvolatile content of 50.0% was obtained.
The average molecular weight of copolymer (5) was approximately 100,000. Next, 15 parts of trimethylolpropane triacrylate as a photopolymerizable monomer was added to 100 parts of the solution of copolymer (5) and mixed with stirring at room temperature to obtain an ultraviolet curable composition (). Comparative Example 3 A comparative copolymer with a nonvolatile content of 49.8% was prepared by repeating the same operation as in Example 6, except that the polymerizable monomer component composition was changed to 35 parts of styrene, 65 parts of butyl acrylate, and 0.1 part of benzoyl peroxide. A solution of (3) was obtained. The average molecular weight of comparative copolymer (3) was about 90,000. Next, bisphenol A was used as a photopolymerizable monomer.
A comparative ultraviolet curable composition (2) was obtained in the same manner as in Example 6 using 15 parts of diacrylate. Comparative Example 4 A flask similar to that used in Example 1 was charged with 100 parts of toluene, and the temperature was raised to 80° C. while slowly flowing nitrogen gas. Next, 35 parts of methyl methacrylate and 65 parts of butyl acrylate prepared in advance were added thereto.
A polymerizable monomer component consisting of 1 part, 4 parts of dodecyl mercaptan, and 1 part of benzoyl peroxide was added dropwise over 3 hours, followed by stirring at the same temperature for 3 hours, and cooling to room temperature to prepare a comparative copolymer (4 parts). ) was obtained. The average molecular weight of the comparative copolymer (4) was about 5,000. Next, 15 parts of trimethylolpropane triacrylate as a photopolymerizable monomer was added to 100 parts of a solution of comparative copolymer (4) and mixed with stirring at room temperature to obtain a comparative composition (2). Example 7 Aqueous dispersion (or solution) of copolymers (1) to (5) obtained in the above examples and comparative examples, aqueous dispersion of comparative copolymers (1) to (4) (or solution), ultraviolet curable composition () to (), comparative composition ()
~() was applied to a glass plate and the performance of the cured film by ultraviolet rays was tested. Preparation of test plate Application to glass plate: Using a bar coater, the coating was applied to a dry film thickness of 10 μm, and water or toluene was evaporated at room temperature. Ultraviolet irradiation: A high-pressure mercury lamp of 120 W/cm was irradiated for about 3 seconds from a distance of 10 cm. Evaluation of film properties: A film that formed a continuous film at room temperature was rated ○, and a film that was not formed was rated ×. Film performance testing method Blocking resistance: Two test plates were placed one on top of the other with the coated side facing inside, and a pressure of 2 kg/cm ² was applied to the 50
After being left at ℃ for 6 hours, the two sheets were peeled off, and those with no abnormality on the painted surface were evaluated as ○, and those with damage were evaluated as ×. Pencil hardness: Compliant with JIS 5400. Water resistance: The samples were immersed in tap water at room temperature for 24 hours, and those with no blisters were evaluated as ○, and those with blisters were evaluated as ×. The test results are shown in Table 1.

[Table] As is clear from Table 1, when the copolymer is within the scope of the present invention, the ultraviolet curable composition obtained by adding the photopolymerizable monomer (B) can initiate photopolymerization. Although the copolymer does not contain any additives, it is cured by ultraviolet irradiation, and the cured film performance is significantly improved compared to the aqueous dispersion (or solution) of the copolymer. In cases outside the scope of the invention, compositions to which the photopolymerizable monomer (B) was added were not cured by ultraviolet light, and the performance was rather lower than that of the comparative copolymers. Furthermore, it is clear that when the copolymer is in the form of an aqueous dispersion, the photopolymerizable monomer acts as a film-forming aid.

Claims (1)

[Scope of Claims] 1 Obtained by (co)polymerizing a polymerizable monomer component containing a methacrylate monomer and/or methyl acrylate in a proportion of 10% by weight or more in the polymerizable monomer component A (co)polymer (A) having an average molecular weight of 10,000 or more and a photopolymerizable monomer (B),
(A): The photopolymerizable monomer (B) is 40 to 98 (in terms of solid content):
An ultraviolet curable composition characterized in that it contains substantially no photopolymerization initiator, containing a photopolymerization initiator in a weight ratio of 60 to 2. 2. The ultraviolet curable composition according to claim 1, wherein the (co)polymer (A) is an aqueous dispersion. 3. The ultraviolet curable composition according to claim 2, wherein the photopolymerizable monomer (B) has a molecular weight of 100 to 1000, a solubility parameter of 8 to 12, and a boiling point of 100°C or higher.